I tried to pick engines that are or were in production, not race car engine that we will NEVER touch. except the 20B thats just a baddass motor. close in my top 5 are all of the M3 motors, just becuase they have ITB's STOCK. also a weird thing is i have THREE 2.0 liters both n/a and the F20 makes alot more power IMO, but the 3S was just used in ANYTHING and everything so its made history IMO.